NSW man embarks on voyage for the ANZACs

For his first trip overseas 54-year-old Mark Keys is setting sail for Gallipoli, the resting place of his great-grandfather Francis Jensen.

Second Lieutenant Jensen was killed on the Turkish peninsula in September 1915, on his third day of battle.

Mr Keys, from Braidwood, NSW, will travel with his wife Germaine and their three sons on the cruise ship Queen Elizabeth.

It will be a significant voyage in many ways.

Mr Keys and his wife have been chosen as custodians of a wall of 11,500 poppies - one each for the Australians and New Zealanders who died in the Gallipoli campaign - which will be carried on the ship.

Sydneysiders have been invited to donate a gold coin and add to the two-metre-high tribute at Circular Quay, which will be formed in the shape of a "100".

They can also leave a message in a commemorative book.

Mr Keys placed one of the flowers on the wall on Tuesday morning, ahead of a moving ceremony on board ship.

"It's a time of great pride and recognition of the struggle that both the soldiers who went over there and the families that were left behind went through," Mr Keys told AAP.

"It's the first chance any of our family have had to get over to Gallipoli and the Lone Pine memorial. It means a lot."

Australian War Memorial Director Dr Brendan Nelson said 62,000 Australians died in the First World War "in our uniform, with our flag, in our name".

He explained that after serving in the Boer War in South Africa, Lieutenant Jensen realised World War One wasn't going to end early so he joined the Australian Imperial Force.

He had a wife and three children waiting for him back in Australia.

"He was part of the front line where he was shot in the face and died the following day," Dr Nelson said at the ceremony.

"We have an obligation to not just settle for the broad brushstrokes of our history, but to remember every single one of these men and 25 women nurses in the First World War who gave their lives for us."